Please use this identifier to cite or link to this item:
http://hdl.handle.net/20.500.12386/31043
Title: | The first blazar observed at z>6 | Authors: | Belladitta, S. MORETTI, Alberto CACCIANIGA, Alessandro Spingola, C. SEVERGNINI, Paola DELLA CECA, Roberto GHISELLINI, Gabriele DALLACASA, DANIELE Sbarrato, Tullia Cicone, C. CASSARA, LETIZIA PASQUA Pedani, M. |
Issue Date: | 2020 | Journal: | ASTRONOMY & ASTROPHYSICS | Number: | 635 | First Page: | L7 | Abstract: | We present the discovery of PSO J030947.49+271757.31, the radio brightest (23.7 mJy at 1.4 GHz) active galactic nucleus (AGN) at z>6.0. It was selected by cross-matching the NRAO VLA Sky Survey and the Panoramic Survey Telescope and Rapid Response System PS1 databases and its high-z nature was confirmed by a dedicated spectroscopic observation at the Large Binocular Telescope. A pointed Neil Gehrels $Swift$ Observatory XRT observation allowed us to measure a flux of $\sim$3.4$\times$10$^{-14}$ erg s$^{-1}$ cm$^{-2}$ in the [0.5-10] keV energy band, which also makes this object the X-ray brightest AGN ever observed at z>6.0. Its flat radio spectrum ($\alpha_{\nu r}$<0.5), very high radio loudness (R>10$^3$), and strong X-ray emission, compared to the optical, support the hypothesis of the blazar nature of this source. %i.e. a radio-loud (RL) AGN with the relativistic jet pointed toward us. Assuming that this is the only blazar at this redshift in the surveyed area of sky, we derive a space density of blazars at z$\sim$6 and with M$_{1450 \mbox{\AA}}$ < -25.1 of 5.5$^{+11.2}_{-4.6}$$\times$10$^{-3}$ Gpc$^{-3}$. From this number, and assuming a reasonable value of the bulk velocity of the jet ($\Gamma$=10), we can also infer a space density of the entire radio-loud AGN population at z$\sim$6 with the same optical/UV absolute magnitude of 1.10$^{+2.53}_{-0.91}$ Gpc$^{-3}$. Larger samples of blazars will be necessary to better constrain these estimates. | URI: | http://hdl.handle.net/20.500.12386/31043 | URL: | https://www.aanda.org/articles/aa/full_html/2020/03/aa37395-19/aa37395-19.html http://arxiv.org/abs/2002.05178v2 |
ISSN: | 0004-6361 | DOI: | 10.1051/0004-6361/201937395 | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
Files in This Item:
File | Description | Size | Format | |
---|---|---|---|---|
aa37395-19.pdf | Pdf editoriale | 8.1 MB | Adobe PDF | View/Open |
Page view(s)
69
checked on Mar 19, 2024
Download(s)
28
checked on Mar 19, 2024
Google ScholarTM
Check
Altmetric
Altmetric
Items in DSpace are published in Open Access, unless otherwise indicated.